linux-kernel - Re: [PATCH v2 0/3] xen: harden blkfront against malicious backends

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Message-ID: <YOj1Spa1hitL61j/@mail-itl>
Date:   Sat, 10 Jul 2021 03:18:02 +0200
From:   Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>
To:     Juergen Gross <jgross@...e.com>
Cc:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        xen-devel@...ts.xenproject.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Roger Pau Monné <roger.pau@...rix.com>,
        Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH v2 0/3] xen: harden blkfront against malicious backends

On Thu, Jul 08, 2021 at 04:39:58PM +0200, Juergen Gross wrote:
> On 08.07.21 16:22, Konrad Rzeszutek Wilk wrote:
> > On Thu, Jul 08, 2021 at 02:43:42PM +0200, Juergen Gross wrote:
> > > Xen backends of para-virtualized devices can live in dom0 kernel, dom0
> > > user land, or in a driver domain. This means that a backend might
> > > reside in a less trusted environment than the Xen core components, so
> > > a backend should not be able to do harm to a Xen guest (it can still
> > > mess up I/O data, but it shouldn't be able to e.g. crash a guest by
> > > other means or cause a privilege escalation in the guest).
> > > 
> > > Unfortunately blkfront in the Linux kernel is fully trusting its
> > > backend. This series is fixing blkfront in this regard.
> > > 
> > > It was discussed to handle this as a security problem, but the topic
> > > was discussed in public before, so it isn't a real secret.
> > 
> > Wow. This looks like what Marek did .. in 2018!
> > 
> > https://lists.xenproject.org/archives/html/xen-devel/2018-04/msg02336.html
> 
> Yes, seems to have been a similar goal.
> 
> > Would it be worth crediting Marek?
> 
> I'm fine mentioning his patches, but I didn't know of his patches until
> having sent out V1 of my series.

Some email issue likely? You were on explicit CC in that series.

> I'd be interested in learning why his patches haven't been taken back
> then.

Mostly it was waiting in limbo on "public: add RING_COPY_RESPONSE()"[1] patch
to the Xen tree, to be then synchronized back to Linux headers. That patch
was finally committed in March this year. I should've followed up on it,
earlier than 3 years later...

[1] https://lore.kernel.org/xen-devel/20180430215436.21062-1-marmarek@invisiblethingslab.com/T/#u

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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